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Author:
Publisher:
ISBN:
Category : Buildings, Reinforced concrete
Languages : en
Pages : 40
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Book Description
Author:
Publisher:
ISBN:
Category : Buildings, Reinforced concrete
Languages : en
Pages : 40
Get Book Here
Book Description
Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 32
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Book Description
The U.S. Army and Air Force have large inventories of concrete frame buildings built before the 1971 San Francisco earthquake, when seismic provisions in U.S. building codes were enhanced. Consequently, many of these buildings may not safely withstand the ground motions associated with large intensity earthquakes. The U.S. Army Construction Engineering Research Laboratories (USACERL) has developed a program to provide improved technologies for mitigating seismic hazards in older military buildings. This study investigated the effectiveness of a nonintrusive rehabilitation technique involving the addition of viscoelastic damping devices to a concrete structure. A one-third scale model of a concrete building was built and placed on the USACERL shaking table. The building was earthquake-tested using two sizes of dampers, and with no dampers in place. Preliminary observations showed that the model with dampers sustained only minimal damage. More detailed analysis continues.
Author:
Publisher:
ISBN:
Category : Reinforced concrete construction
Languages : en
Pages : 188
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Book Description
Author: John R. Hayes
Publisher:
ISBN:
Category : Buildings, Reinforced concrete
Languages : en
Pages : 921
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Book Description
The objective of this study was to develop improved understanding of the seismic behavior of a lightly reinforced concrete (LRC) slab-column structure seismically retrofitted with viscoelastic dampers (VEDs). The feasibility of using VEDs to rehabilitate existing LRC slab-column structures was explored, and implications for structural design were considered. A model of a section of a 1950s-era three-story military barracks building was fabricated for testing. A rehabilitation scheme using VEDs was designed and implemented. This section model was subjected to a series of earthquake simulations on the shaking table at the U.S. Army Construction Engineering Research Laboratories (CERL). Experimental measurements included floor and VED displacements, floor accelerations, VED forces, and reinforcement strains. The earthquake simulations comprised a series of gradually increasing intensity replications of two commonly used earthquake records, first on the frame fitted with VEDs, then on the frame without VEDs. Interpretations of the testing results are provided through the use of linear models of the type that might be used in the design office. These analytical models also were used to assess the applicability of the linear modeling procedures that have been recommended in Federal Emergency Management Agency document 273, "NEHRP Guidelines for the Seismic Rehabilitation of Buildings."
Author: Sachin Kuckian
Publisher: GRIN Verlag
ISBN: 3668992762
Category : Science
Languages : en
Pages : 90
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Book Description
Master's Thesis from the year 2015 in the subject Engineering - Geotechnology, grade: 9.44, , course: Masters (Structural Engineering), language: English, abstract: The present study investigates the seismic behavior of multi-story building using damping devices strategically located within the lateral load resisting elements. It concentrates on a retrofitting strategy with passive energy dissipation device known as Fluid Viscous Damper (FVD) which will be applicable to new design as well as retrofitting existing buildings to ensure seismic safety by fitting damping devices which can transform a wall panel into a damping element. The first study involves analysis of a nine-story model having cut-outs and the use of the dampers of different configuration in these structures. The second study involves the use the diagonal brace configuration dampers provided in the cutout sections of 2D 9, 18, 27 storey structures and 3D 27 storey with core wall structure at three consecutive story levels each. For the second study, the cut out locations is varied depending on their relative positions. The relative position is the ratio of the total height of the structure to the upper edge of the topmost cut-out. These structures were initially modeled and time history analysis was performed on the structure without FVD and the structure retrofitted with FVD. Three different ground motions were used for the analysis. Results of the un- retrofitted structures are then compared with a retrofitted structure in terms of peak story displacements, roof accelerations, and pseudo-spectral accelerations. Study shows that there has been a significant reduction in seismic demands for a structure retrofitted with FVD in terms of peak storey displacements, pseudo-spectral accelerations and roof accelerations when the dampers are placed at lower three cut outs i.e. with high relative position. It is also observed that damping coefficient value obtained is least for upper toggle-brace configuration out of the four different damper configurations and with maximum reduction compared to other configurations. For modeling and analysis purpose the software SAP2000® is used. Through the study it could be concluded that FVD significantly reduces the seismic demands of the structure in terms of peak storey displacements, pseudo-spectral accelerations and roof accelerations. This suggests that FVDs can be efficiently used in retrofitting. Also damping coefficient value obtained is least for upper toggle-brace configuration out of the four different damper configurations suggesting this is the most efficient configuration for retrofitting.
Author:
Publisher:
ISBN:
Category : Juvenile Nonfiction
Languages : en
Pages : 74
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Book Description
This renamed version of the former Uniform code for building conservation guidelines for retrofitting unreinforced masonry bearing wall buildings, reinforced concrete and reinforced masonry buildings, wood frame residential buildings, and concrete with masonry infill buildings.
Author:
Publisher:
ISBN: 9781642241815
Category :
Languages : en
Pages : 375
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Book Description
Seismic retrofitting is the modification of existing structures to make them more resistant to seismic activity, ground motion, or soil failure due to earthquakes. The planning of changes to existing buildings differs from new planning through an important condition; the existing construction must be taken as the basis of all planning and building actions. The need for seismic retrofitting of an existing building can arise due to several reasons like: building not designed to code, subsequent updating of code and design practice, subsequent upgrading of seismic zone, deterioration of strength and aging, modification of existing structure, change in use of the building, etc. Seismic retrofit is primarily applied to achieve public safety, with various levels of structure and material survivability determined by economic considerations. In recent years, an increased urgency has been felt to strengthen the deficient buildings, as part of active disaster mitigation, and to work out the modifications that may be made to an existing structure to improve the structural performance during an earthquake. Seismic retrofitting schemes can be either global or local, based on how many members of the structures they are used for. Global Retrofit methods include conventional methods (increase seismic resistance of existing structures) or non-conventional methods (reduction of seismic demand). Strengthening and Retrofitting of Existing Structures is a compendium of cutting-edge trends of the research and existing practices in strengthening and retrofitting of structural elements, as well as the findings of a research endeavor initiated by the authors to investigate and develop a robust structural retrofitting scheme by utilizing elastomeric polymers to enhance the resistance of reinforced concrete (RC) structures. It addresses in detail specific techniques for the strengthening of traditional constructions, reinforced concrete buildings, bridges and their foundations. It also presents insight into the key issues relevant to seismic retrofit of concrete frame buildings. Many guidelines are reviewed regarding seismic rehabilitation of school, office, hospital and apartment buildings.
Author: Sarven Akçelyan
Publisher:
ISBN:
Category :
Languages : en
Pages :
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Book Description
"A number of existing tall steel buildings in seismic regions may have potential deficiencies to seismic events with low probability of occurrence. It is understood that the seismic performance of such buildings should be evaluated thoroughly such that effective retrofit solutions can be proposed. In this thesis, the emphasis is on the implementation of supplemental damping devices, particularly, nonlinear viscous damper (NVDs), oil dampers with relief valves (ODs) and buckling-restrained braces (BRBs). In the context of performance based design there is an increased need to improve the reliability of state-of-art and simplified evaluation methods for tall buildings equipped with supplemental damping devices. This research presents enhanced models and algorithms for the numerical simulation of NVDs, ODs and BRBs within a nonlinear finite element program. Adaptive algorithms are implemented for computing high-precision solutions for NVDs and ODs that are typically represented mathematically with a nonlinear Maxwell model. Furthermore, a novel rate-dependent material model for BRBs and its calibration procedure with experimental data is developed. The applicability and computational efficiency of the numerical models is demonstrated through a number of validation examples with data that involve component experimentation as well as the utilization of full-scale shake table tests of a 5-story steel building equipped with supplemental damping devices. Based on a comparison of various engineering demand parameters with experimental data, it is shown that linear and nonlinear static procedures as per ASCE 41-13 may be unconservative for the evaluation of frame buildings with BRBs or NVDs, while the performance curves and P-Spectra methods provide more reliable predictions. In order to enhance current design methods for dampers in tall buildings, a practical multi-degree-of-freedom (MDF) performance curves tool is developed. The advantage of this tool over currently used methods is that the designer can directly obtain story-based EDPs for a range of design solutions, which do not contain typical errors due to transformation, (i.e. SDF idealization, higher modes, flexural deformations, irregular damping distribution) and linearization. A comprehensive study related to the seismic performance assessment of a benchmark existing 40-story steel building with moment-resisting frames that represents typical 1970s construction in North America is presented. Supplemental damping provided by ODs is utilized to design an efficient seismic retrofit system for the 40-story steel building under consideration. Multiple retrofit solutions are designed based on three damping levels. It is shown that the formation of local story collapse mechanisms can be prevented and the drift distribution can be controlled along the height of the building. The efficiency of vertical damping distribution methods varies with the level of the frame inelasticity." --
Author: Stelios Antoniou
Publisher: John Wiley & Sons
ISBN: 1119987326
Category : Technology & Engineering
Languages : en
Pages : 549
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Book Description
Seismic Retrofit of Existing Reinforced Concrete Buildings Understand the complexities and challenges of retrofitting building infrastructure Across the world, buildings are gradually becoming structurally unsound. Many were constructed before seismic load capacity was a mandatory component of building standards, and were often built with low-quality materials or using unsafe construction practices. Many more are simply aging, with materials degrading, and steel corroding. As a result, efforts are ongoing to retrofit existing structures, and to develop new techniques for assessing and enhancing seismic load capacity in order to create a safer building infrastructure worldwide. Seismic Retrofit of Existing Reinforced Concrete Buildings provides a thorough book-length discussion of these techniques and their applications. Balancing theory and practice, the book provides engineers with a broad base of knowledge from which to approach real-world seismic assessments and retrofitting projects. It incorporates knowledge and experience frequently omitted from the building design process for a fuller account of this critical engineering subfield. Seismic Retrofit of Existing Reinforced Concrete Buildings readers will also find: Detailed treatment of each available strengthening technique, complete with advantages and disadvantages In-depth guidelines to select a specific technique for a given building type and/or engineering scenario Step-by-step guidance through the assessment/retrofitting process Seismic Retrofit of Existing Reinforced Concrete Buildings is an ideal reference for civil and structural engineering professionals and advanced students, particularly those working in seismically active areas.
Author: John R. Hayes
Publisher:
ISBN:
Category : Buildings, Reinforced concrete
Languages : en
Pages : 921
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Book Description
The objective of this study was to develop improved understanding of the seismic behavior of a lightly reinforced concrete (LRC) slab-column structure seismically retrofitted with viscoelastic dampers (VEDs). The feasibility of using VEDs to rehabilitate existing LRC slab-column structures was explored, and implications for structural design were considered. A model of a section of a 1950s-era three-story military barracks building was fabricated for testing. A rehabilitation scheme using VEDs was designed and implemented. This section model was subjected to a series of earthquake simulations on the shaking table at the U.S. Army Construction Engineering Research Laboratories (CERL). Experimental measurements included floor and VED displacements, floor accelerations, VED forces, and reinforcement strains. The earthquake simulations comprised a series of gradually increasing intensity replications of two commonly used earthquake records, first on the frame fitted with VEDs, then on the frame without VEDs. Interpretations of the testing results are provided through the use of linear models of the type that might be used in the design office. These analytical models also were used to assess the applicability of the linear modeling procedures that have been recommended in Federal Emergency Management Agency document 273, "NEHRP Guidelines for the Seismic Rehabilitation of Buildings."
